Use CKEditor 5's native <ol start> support (and also support <ol reversed>)

Created on 31 January 2022, almost 3 years ago

Updated 26 October 2023, about 1 year ago

We "solved" the problem of supporting <ol start> by using the SourceEditing functionality for that.

But in CKEditor 5 32.0.0, they've added native support for <ol start> (and even for <ol reversed>).

Which means that rather than having to edit HTML by hand, the content creator can now do that through the UI!

N/A

Use it!

After Drupal is updated to that version of CKEditor 5, we should modify the ckeditor5_list plugin definition to:

have a plugin class that allows the site builder to configure the list functionality to specify the starting index and whether the ordered list should be reversed (two separate booleans to store). See \Drupal\ckeditor5\Plugin\CKEditor5Plugin\Heading for an example — note this will also require an addition to the config schema, but that too has an example
this should cause \Drupal\Tests\ckeditor5\Kernel\SmartDefaultSettingsTest to fail — because a better upgrade path becomes possible, so we should update that test coverage